Infrared and ultraviolet radiation absorbing glass

ABSTRACT

An infrared and ultraviolet radiation absorbing glass having a green tint, more particularly, an infreared and ultraviolet radiation absorbing glass having high transmission and pale bluish green tint which is suitable for use as a glass for automobiles or a glass for construction.  
     The infrared and ultraviolet radiation absorbing glass comprises, in % by weight:  
     a soda-lime-silica basic glass, and  
     coloring components comprising  
     0.40 to less than 0.58% total iron oxide (T—Fe 2 O 3 ) in terms of Fe 2 O 3 ,  
     0.05 to less than 0.5% CeO 2 ,  
     0 to 0.5% TiO 2 , and  
     0.0001 to 0.002% CoO,  
     wherein 20 to less than 30% of T—Fe 2 O 3  is FeO in terms of Fe 2 O 3 .

TECHNICAL FIELD

[0001] The present invention relates to an infrared and ultravioletradiation absorbing glass having a green tint. More particularly, itrelates to an infrared and ultraviolet radiation absorbing glass havinghigh transmission and pale bluish green tint which is suitable for useas a glass for automobiles or a glass for construction.

BACKGROUND ART

[0002] In recent years, interior trim of automobiles tends to be luxury,and from the standpoint of the demand to protect the interior trim fromdeterioration and reduce load of air conditioning, a green-tined glasshaving infrared and ultraviolet radiation absorbing power impartedthereto has been proposed as window glass of automobiles.

[0003] For example, JP-A-4-310539 (the term “JP-A” used herein means an“unexamined published Japanese patent application”) discloses aninfrared and ultraviolet radiation absorbing glass consistingessentially of, in % by weight, 65-75% SiO₂, 0.1-5% Al₂O₃, 10-18% Na₂O,0-5% K₂O, 5-15% CaO, 1-6% MgO and 0.05-1.0% SO₃, and having incorporatedtherein as coloring components, 0.5-1.2% total iron oxide in terms ofFe₂O₃, 0.1-3.0% CeO₂ and 0-1.0% TiO₂, wherein 20-40% of the total ironoxide in terms of Fe₂O₃ is FeO.

[0004] JP-A-5-78147 discloses an infrared and ultraviolet radiationabsorbing glass as a glass having relatively pale green tint in variousinfrared and ultraviolet radiation absorbing glasses. This glasscomprises, in % by weight, basic components comprising 68-72% SiO₂,1.6-3.0 Al₂O₃, 8.5-11.0% CaO, 2.0-4.2% MgO, 12.0-16.0% Na₂O, 0.5-3.0%K₂O and 0.5-3.0% SO₃, and coloring components comprising 0.58-0.65%total iron oxide in terms of Fe₂O₃, 0.1-0.5% CeO₂, 0.1-0.4% TiO₂ and10-350 ppm MnO as a trace oxide.

[0005] JP-A-6-56466 discloses a glass having low total solar energytransmission and ultraviolet transmission. This glass comprises, in % byweight, a soda-lime-silica basic glass, and having incorporated therein0.53-0.70% total iron oxide in terms of Fe₂O₃, 0.35-0.50% Fe₂O₃,0.16-0.24% FeO, 0.2-0.4% TiO₂, and 0.5-0.8% total cerium in terms ofCeO₂, wherein an amount of FeO in terms of Fe₂O₃ is 30-40% based on theweight of the total iron oxide in terms of Fe₂O₃.

[0006] In the infrared and ultraviolet radiation absorbing glassdisclosed in the above-described JP-A-4-310539, the coloring componentsare preferably 0.7-1.0% total iron oxide in terms of Fe₂O₃, and 0.3-2.0CeO₂, and a visible light transmission when the glass has a thickness of5 mm is 66.1-66.8% as shown in the examples. As is understood from this,a green tint of the glass is comparatively dark. However, in some casessuch a dark tint may not be preferred as a glass for automobiles, or isnot generally preferred as a glass for construction.

[0007] In the infrared and ultraviolet radiation absorbing glassdisclosed in the above-described JP-A-5-76147, the preferred range ofthe total iron oxide in terms of Fe₂O₃ is about 0.6-0.64%. In this case,a visible light transmission is at most about 71%, and thus it cannotsay that the visible light transmission is sufficiently high.

[0008] The infrared and ultraviolet radiation absorbing glass disclosedin the above-described JP-A-6-56466 includes an infrared and ultravioletradiation absorbing glass having relatively high visible lighttransmission. However, in order to obtain high total solar energyabsorbing power, an amount of divalent iron in terms of Fe₂O₃ is 30-40%by weight based on the weight of the total iron in terms of Fe₂O₃. As aresult, melting under stronger reducing condition than the general isrequired. Further, the total cerium in terms of CeO₂ is 0.5-0.8%, whichis relatively large. This results in making it difficult to conductmelting under strong reducing condition, and also increases raw materialcost.

DISCLOSURE OF THE INVENTION

[0009] The present invention has been made in view of theabove-described problems in the prior art.

[0010] Accordingly, an object of the present invention is to provide aninfrared and ultraviolet radiation absorbing glass having green tint,and in particular an infrared and ultraviolet radiation absorbing glasshaving high transmission and pale bluish green tint which is suitablefor use as a glass for automobiles or a glass for construction.

[0011] According to the present invention, there is provided an infraredand ultraviolet radiation absorbing glass comprising, in % by weight:

[0012] a soda-lime-silica basic glass, and

[0013] coloring components comprising

[0014] 0.40 to less than 0.58% total iron oxide (T—Fe₂O₃) in terms ofFe₂O₃,

[0015] 0.05 to less than 0.5% CeO₂,

[0016] 0 to 0.5% TiO₂, and

[0017] 0.0001 to 0.002% CoO,

[0018] wherein 20 to less than 30% of T—Fe₂O₃ is FeO in terms of Fe₂O₃.

[0019] The content of TiO₂ is preferably 0 to less than 0.2%, morepreferably 0 to less than 0.1%.

[0020] The infrared and ultraviolet radiation absorbing glasscomposition preferably further comprises 200 ppm or less of MnO.

[0021] The infrared and ultraviolet radiation absorbing glass preferablyhas, when the glass has a thickness of 3.25 to 6.25 mm, opticalcharacteristics such that a visible light transmission measured with CIEstandard illuminant A at a wavelength region of 380 to 770 nm is 75% ormore, a dominant wavelength measured with CIE standard illuminant C at awavelength region of 380 to 770 nm is 490 to 515 nm, a total solarenergy transmission measured at a wavelength region of 300 to 2,100 nmless than 55%, and an ultraviolet transmission defined by ISO 9050 isless than 20%.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] The reason for limitations of the glass composition of theinfrared and ultraviolet radiation absorbing glass according to thepresent invention are described below. Unless otherwise indicated, all %are by weight.

[0023] The soda-lime-silica basic glass used herein means a generalfloat composition, but maybe a composition for thin plate in whichcontents of SiO₂, alkali oxides and alkaline earth oxides are increasedor decreased to increase a coefficient of thermal expansion or Young'smodulus of a glass, thereby facilitating thermal tempering, and acomposition in which absorption position of coloring components ischanged.

[0024] The iron oxide is present in a glass in the form of Fe₂O₃ andFeO. Fe₂O₃ is a component to enhance the ultraviolet absorbing powertogether with CeO₂ and TiO₂, and FeO is a component to enhance theabsorption power of solar heat rays.

[0025] In order to obtain desired visible light transmission and totalsolar energy absorbing power, the content of the total iron oxide(T—Fe₂O₃) must be in a range of 0.40 to less than 0.58%, and theproportion of FeO to T—Fe₂O₃ (the amount of FeO is generally a value interms of Fe₂O₃) must be in a range of 20 to less than 30%. If the totaliron content and the proportion of FeO to T—Fe₂O₃ are lower than therespective lower limit of the above ranges, the total solar energyabsorbing power becomes insufficient, and on the other hand, if thoseare higher than the respective upper limit of the above ranges, thevisible light transmission becomes too low.

[0026] In order to obtain a desired ultraviolet absorbing effect in suchtotal iron oxide content and proportion of FeO to T—Fe₂O₃, the CeO₂content must be within a range of 0.05 to less than 0.5%. If the CeO₂content is less than 0.05%, the ultraviolet absorbing effect is notsufficient, and on the other hand, if it is 0.5% or more, absorption ofvisible light at a short wavelength side is too large, so that a desiredcolor tint is not obtained and also cost of raw materials increases.

[0027] TiO₂ is not an essential component, but can be added in anappropriate amount such that the optical characteristics intended in thepresent invention are not impaired, in order to increase the ultravioletabsorbing power of a glass. If the TiO₂ content is too large, a glasstends to color yellow. For this reason, the upper limit of the TiO₂content is generally 0.5%, preferably less than 0.2%, and morepreferably less than 0-1%.

[0028] CoO, although in a slight content, is an essential component,which is important to prevent the color tint from being yellowed in thecase of containing iron oxide and cerium oxide together, and to adjustcolor tint of a glass to a preferable bluish green. The CoO content isusually 0.0001 to 0.002%.

[0029] MnO is not an essential component, but is a component effectiveto a dust color tint of a glass in the case of containing iron oxide andcerium oxide together, and the proportion of FeO to T—Fe₂O₃. If the MnOcontent increases, coloration by itself affects a glass. For thisreason, the upper limit of the MnO content is 200 ppm.

[0030] SnO₂ may be added as a reducing agent to the glass having theabove-described components, in an amount of up to 1%. Further, at leastone of Cr₂O₃, NiO, V₂O₅, MoO₃ and the like may be added as a coloringagent as conventional in an amount such that the objective pale greencolor tint in the present invention is not impaired. The coloring agentsmay be added simultaneously.

EXAMPLES

[0031] The present invention is described below in more detail by thefollowing examples, but the invention should not be limited thereto.

[0032] Soda-lime-silica basic glass composition used in the examples andthe comparative examples comprises, in % by weight:

[0033] 72.0% SiO₂,

[0034] 1.61% Al₂O₃,

[0035] 8.02% CaO,

[0036] 4.05% MgO,

[0037] 13.2% Na₂O,

[0038] 0.52% K₂O, and

[0039] 0.19% SO₃.

Examples 1 to 4 and Comparative Examples 1 to 3

[0040] Each of mixed raw materials comprising the above soda-lime-silicabasic glass composition and coloring agents (each content is shown in %by weight) shown in Table 1 below was prepared using quartz sand,limestone, dolomite, soda ash, salt cake (sodium sulfate), ferric oxide,titanium oxide, cerium oxide, slug and carbonaceous reducing agent. Theresulting mixed batch was melted in an electric furnace at 1,450° C. for4 hours. The molten glass was cast on a stainless steel plate andannealed to room temperature to obtain glass samples each having athickness of about 10 mm. The concentrations shown in the Tables are allwt % representation except that CoO is ppm representation. TABLE 1Example Comparative Example 1 2 3 4 1 2 3 Total iron oxide 0.45 0.500.53 0.57 0.45 0.53 0.58 FeO ratio* 25 25 25 22.5 22.5 25 22.5 CeO₂ 0.490.40 0.30 0.20 0.60 0.30 0.30 TiO₂ 0.03 0.03 0.05 0.07 0.03 0.03 0.05CoO 1 3 2 6 0 0 0

[0041] Each glass obtained was polished to have a thickness of about 5mm. A visible light transmission (YA) measured with the CIE standardilluminant A, a dominant wavelength (Dw), chromaticities expressed as aand b of the Lab coordinates, an excitation purity (Pe) (measured withthe CIE standard illuminant C), an ultraviolet transmission (Tuv)defined by ISO 9050, and a total solar energy transmission (TG) weremeasured as optical characteristics of each glass.

[0042] Optical characteristics of the glass samples obtained are shownin Table 2 below. TABLE 2 Example Comparative Example 1 2 3 4 1 2 3 YA79.5 77.3 76.9 75.2 79.3 77.6 77.2 TG 54.9 53.3 52.0 51.7 58.3 52.3 52.3Tuv 19.8 19.2 18.6 17.9 16.1 18.6 16.6 Dw 496 495 496 496 504 498 502 Pe2.80 3.38 3.32 3.48 1.82 3.00 2.45 a −5.83 −6.47 −6.84 −6.85 −5.55 −6.84−6.95 b −0.08 −0.39 −0.08 −0.25 1.10 0.32 1.18

[0043] As is apparent from Table 2 above, the glass samples obtained inthe Examples have optical characteristics that a visible lighttransmission (YA) measured with the CIE standard illuminant A is 75% orhigher, an ultraviolet transmission (Tuv) defined by ISO 9050 is lessthan 20%, and a total solar energy transmission (TG) is less than 55%.Further, in view of the facts that the dominant wavelength (Dw) measuredwith the CIE standard illuminant C is around 495 nm, and thechromaticity expressed as b of the Lab coordinates is minus, it isapparent that the glass samples obtained in the Examples are a glasshaving a bluish green tint which is a favorable color tint as glassesfor automobiles, and the like.

[0044] Contrary to this, the glass samples obtained in the ComparativeExamples have optical characteristics that a dominant wavelengthmeasured with the CIE standard illuminant C is about 498 to 504 nm, andthe chromaticity expressed as b of the Lab coordinates is plus. Thisshows that differing from the glasses obtained in the Examples, thoseglasses have yellowish green tint which is not a favorable color tint asglasses for automobiles, and the like.

[0045] Industrial Applicability

[0046] As described in detail above, the present invention can producethe infrared and ultraviolet radiation absorbing glass havingappropriate solar heat absorbing power and ultraviolet absorbing powerwhile maintaining high visible light transmission without coloring indark green.

[0047] Further, the infrared and ultraviolet radiation absorbing glassaccording to the present invention maintains pale green color tint andhigh visible light transmission, and therefore is particularly useful inthe case that a pale color tint is favorable, or as glasses forautomobiles or glasses for construction, that are used after applicationof a coating film.

1. An infrared and ultraviolet radiation absorbing glass comprising, in% by weight: a soda-lime-silica basic glass, and coloring componentscomprising 0.40 to less than 0.58% total iron oxide (T—Fe₂O₃) in termsof Fe₂O₃, 0.05 to less than 0.5% CeO₂, 0 to 0.5% TiO₂, and 0.0001 to0.002% CoO, wherein 20 to less than 30% of T—Fe₂O₃ is FeO in terms ofFe₂O₃.
 2. The infrared and ultraviolet radiation absorbing glass asclaimed in claim 1, wherein the content of TiO₂ is 0 to less than 0.2%.3. The infrared and ultraviolet radiation absorbing glass as claimed inclaim 1, wherein the content of TiO₂ is 0 to less than 0.1%.
 4. Theinfrared and ultraviolet radiation absorbing glass as claimed in any oneof claims 1 to 3, which further comprises 200 ppm or less of MnO.
 5. Theinfrared and ultraviolet radiation absorbing glass as claimed in any oneof claims 1 to 4, wherein the glass has, when the glass has a thicknessof 3.25 to 6.25 mm, a visible light transmission determined with CIEstandard illuminant A of 75% or more.
 6. The infrered and ultravioletradiation absorbing glass as claimed in any one of claims 1 to 5,wherein the glass has, when the glass has a thickness of 3.25 to 6.25mm, an ultraviolet transmission defined by ISO 9050 of less than 20%. 7.The infrared and ultraviolet radiation absorbing glass as claimed in anyone of claims 1 to 6, wherein the glass has, when the glass has athickness of 3.25 to 6.25 mm, a total solar energy transmission of lessthan 55%.
 8. The infrared and ultraviolet radiation absorbing glass asclaimed in any one of claims 1 to 7, wherein the glass has, when theglass has a thickness of 3.25 to 6.25 mm, a dominant wavelengthdetermined with CIE standard illuminant C at a wavelength region of 490to 515 nm.